Heater circuit function

General function requirements

 Engine running

Heater circuit function

The coolant pump pumps cold coolant through the engine. The coolant absorbs the engine's heat and becomes heated. Then some of the heated coolant is routed through the heater heat exchanger, where the heat is delivered to the interior air.

Most of the coolant does not flow through the heater heat exchanger, but rather from the engine to the coolant thermostat.

Depending on the coolant temperature, it routes the coolant through the radiator or directly through the engine again.

The coolant circulation pump (M13/5) is used to support the coolant pump at low engine speeds and to implement the residual engine heat utilization function.

The coolant circulation pump is actuated by the front SAM control unit with fuse and relay module (N10/1) when requested by the automatic air conditioning control and operating unit (N22/7).